98 S70 electrical issues Topic is solved

[scot850]

There are a few in the engine bay. I can't recall them all but start with the battery negative connection and the ground that runs under the battery tray if I recall, and another piece runs down to the front of the block. That one gets corroded.

There ia another ground to the inner fender on the front of the LH front strut.

Then there is the ground at the middle rear of the engine to the firewall. That one can go bad through corrosion and high resistance.

Not sure on a 98 but there is another I think that runs from the engine rear on the RHS to the RH inner fender.

Again can't recall if there is one on the RH inner fender near the hood lock.

I'm also thinking it is worth checking the wire to the starter and at the starter connections for corrosion.

Neil.

[shegarty]

Awesome Neil, I’ll look into all of these over the weekend

[misha]

Check voltage drop from b+ on the alternator to positive battery terminal,starter positive terminal to battery positive and from alternator housing to negative battery terminal.

Test must be performed after at least 30min of driving with headlights,heater blower around the middle and radio ON and without turning the engine off prior to testing.

Your alternator is perfect.

[crlande]

Hello Misha,
I knew you would chime in on this issue!!!
I was just telling a Honda owner a few days ago, as I was swapping their alternator out, about how you guided me thru my alternator issue. Followed your instructions.... then run outside, do the test...run back in and give results. Follow next instructions, run back outside, etc. too funny!!
Carl

[shegarty]

Smoking gun found ...

IMG_3243.JPG (204.89 KiB) Viewed 370 times

IMG_3244.JPG (154.08 KiB) Viewed 370 times

Looks like a household wire clamp for the main engine ground. With a couple of wiggles back and forth it completely broke off (second pic). It's been replaced with a proper lug but I did notice that the original cable was a bit firm and not as flexible as it should be, there was also some corrosion under the insulation. Resistance still tests fine on the ground wire but I'll put it on the list of future maintenance items. It was a bit difficult to get at as I had to remove the battery tray and the main charge pipe but not a total nightmare. System now puts out a healthy 14.2V to the battery at idle and 13.7-13.9V with the engine hot and under full load (heater, lights, rear defroster, heated seats) with only about 150mV drop from alternator to battery. Thanks everyone for the suggestions.

EDIT: I just read a previous post ... I was the one that put that cable clamp on don't know what I was thinking but at the time I was chasing a no start issue that was a huge pain in the ass! Lesson learned

[scot850]

How long did it work?? We all learn and in my case, I keep learning as nothing is straightforward on cars. Mind you I am possibly going to have to embark on a voyage of discovery on an 06 V50 T5 AWD. I am already looking for my running shoes to head for the hills! ECU, TCU (replacement engine may be from an auto into a manual car), alternator changes between years and associated CM's that may or may not be compatible and need reprogramming to stop the car frying alternators and batteries. I'm hoping it is a grounding issue!!

Hopefully all is well after you replace the connector and crimp.

Neil.

[shegarty]

I think it lasted for like 5 years so not a total fail. Charging system seems to be much happier now. Good luck with the V50!

[abscate]

Nice detective work ,shegarty!

Foggy, vtl, Misha, Scot for the win

[foggydogg]

Nice detective work ,shegarty!

Foggy, vtl, Misha, Scot for the win

I always try to be well-grounded.